The most common type of insect sting allergy is caused by honey bees followed by vespids which include hornets, yellowjackets and wasps. Vespid venom contains three major allergens: hyaluronidase, phospholipase A1 and an antigen 5 of as yet unknown biological function. The cDNA and the protein sequences of homologous antigen 5s and phospholipases A1 from several vespids are known and the sequences of homologous hyaluronidases are being investigated. Having the sequence data of families of homologous vespid venom proteins can facilitate the structure-function analysis of these allergen molecule. The first aspect of the proposed work is to map the major B and T cell epitopes of vespid venom allergens. The epitopes will be mapped by testing various fragments of venom allergens ford their binding of venom-specific antibodies, and for their stimulation of venom-specific T cells. The necessary fragments will be prepared by recombinant technology and/or chemical degradation of natural or recombinant venom proteins. The second aspect of the proposed work is to study whether there is antigenic cross reactivity of vespid antigen 5s with mammalian testis proteins and vespid phospholipases with mammalian lipases as these proteins are found to have sequence similarity. The third aspect of the proposed work is to study tolerance induction in mice with T and B cell epitope peptides of venom allergens. These studies will be made first with the bee venom allergen melittin as this 26-residue peptide has one major epitope each for the T and B cells. Preliminary findings suggest that one melittin analog can suppress antibody response to melittin in mice. A knowledge of the B and T cell epitopes of vespid venom allergens will help to clarify the common clinical observation of multiple sensitivity of insect allergic patients which can be due to exposure to different vespids and/or cross reactivity of vespid allergens. Data on epitopes of different allergens can help our understanding of what makes an allergen. If tolerance can be induced efficiently in vivo with T and B cell epitope peptides, this will be a useful alternative to the standard immunotherapy with allergen extracts.